1. Field of the Invention
The present invention relates to lighting systems and, more particularly, to reflector type fixtures optimized for use in an industrial or commercial facility.
2. Background of the Invention
Fluorescent lighting fixtures are used in various applications such as being recessed in hung ceilings or being used as stand-alone units hung, for example, from the rafters of an industrial or commercial building. Traditionally, fluorescent lighting fixtures have been used in such recessed applications because they generate much less heat than other types of lighting units, e.g., high intensity discharge, and because they may have a physical package with a short height and/or a small width (depending on the number of tubes in the fixture).
Many areas in stores, warehouses, and commercial buildings are illuminated by various free-standing types of lighting fixtures that may be suspended from the ceiling, such lighting fixtures typically containing lamps such as mercury vapor, metal halide, or sodium types. Industrial or commercial lighting may be classified as being high bay or low bay, depending on a nominal height of the fixture above the floor of the room being illuminated. In most lighting applications it is desirable to direct the light downward, for example, to illuminate aisles in a store or warehouse, as necessary in a building having a high bay. As a low-power, low-cost alternative to expensive high intensity discharge (HID) type lamps that may generate excessive heat, require expensive and heavy ballasts, or that may be of a design not readily adaptable to different lighting applications, many commercial lighting installations utilize fluorescent lamp fixtures. Such fluorescent fixtures may have a lower wattage requirement and cost. Other reasons may dictate choosing fluorescent fixtures, for example, lower temperatures, smaller and lighter ballasts, power distribution requirements, lower intensity, etc. Although it may be advantageous to provide fluorescent lighting in these applications, it may be difficult to provide the necessary efficiency and directivity. A higher efficiency is desirable, for example, to reduce the number of luminaries to produce the necessary level of illumination. In addition, traditional luminaries may be inadequate, for example, in buildings such as warehouses, which have high ceilings necessary to accommodate high stacking and shelving of items.
Fluorescent lighting systems may be implemented as so-called “compact” fluorescent devices, as well as conventional “linear” fluorescent fixtures. The newer compact devices typically utilize smaller diameter, shorter fluorescent tubes that may be formed in a “U”. For lighting fixtures of both the compact and linear fluorescent type it may be difficult to adapt to various lighting requirements and applications in a high bay. Traditional high bay lighting may not be optimized because, although it is important that light be efficiently directed downwardly from a high location onto an illuminated surface, many high bay lighting situations may include areas that require less light some or all of the time.